JP2003154527A - Tire vulcanizing mold and tire manufactured by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire vulcanizing mold or the like which enables effective venting of air in the vulcanizing mold on the occasion of vulcanizing molding even when the number of provided ventholes is lessened in comparison with that of a usual vulcanizing mold. SOLUTION: The tire vulcanizing mold has a constitution wherein blades 3 for forming sipes and the ventholes 4 for venting air are provided in the inner surface 2 of the mold and a padding part 8 of which the surface is a slant 7 having a linear sectional shape is provided in a corner part 6 formed by the blade 3 and the inner surface 2 of the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire vulcanizing mold having a sipe forming blade and an air vent vent hole on the inner surface of the mold, and a tire manufactured using the mold.

[0002]

2. Description of the Related Art A tire, for example, a tire having a block pattern, is usually provided with three or more sipes in each block from the viewpoint of enhancing the edge effect on a snowy and snowy road surface.

In order to manufacture such a tire, it is necessary to set a green tire in a vulcanization mold in which a sipe forming blade or the like is placed, and then vulcanize and mold it.
This vulcanization molding is performed in a state where the blade is inserted in the block that constitutes the land portion of the tread of the green tire.

At this time, the rubber of the green tire flows in the space sandwiched between the blades on the inner surface of the mold, but this rubber usually contains air therein, and this air remains in the inside. When vulcanization molding is performed, the tread surface of the tread portion of the tire has a surface defect called a so-called crown bear, which becomes an avatar shape because it is not partly molded.

As a means for preventing the generation of such a crown bear, as shown in FIG. 3, between the blades 102, 102 on the inner surface of the mold 100 and between the groove forming projection 103 and the blade 10.
It is useful to employ a configuration in which a vent hole 105 is provided for each of the small sections 104 sandwiched between the two, and the air in the mold 100 is discharged to the outside through these vent holes 105.

However, when the vent hole 105 is provided, the vent hole 10 is formed on the surface of the tire after vulcanization molding.
Rubber called so-called spew that bulges out of 5 is inevitably generated, and such spew must be removed in the finishing step that is performed after that.In addition, even if spew is removed, spew is still present on the tire surface. Traces still remain, and such spew traces cause the problem of non-uniformity of tire contact pressure and deteriorate the surface appearance of the tire.

Therefore, in the conventional vulcanization mold 100 in which the vent hole 105 is arranged for each small section 104 sandwiched between the blades 102, 102 on the inner surface 101 of the mold, a large number of spews are formed on the tire surface. As a result, the above problem becomes prominent.

Therefore, it is preferable to reduce the number of spews formed on the tire surface, because the number of man-hours in the removing work can be reduced and the surface appearance of the tire after the removing work can be improved.

However, in order to reduce the number of spews, if the number of vent holes 105 provided in the conventional vulcanization mold 100 is simply reduced, as shown in FIG. Corner formed by blade 102 and mold inner surface 101
The rubber 107 of the tire cannot be sufficiently moved up to 106 and a gap 108 is likely to be generated, and if the vent hole 105 is not provided between the blades 102, 102, the corner portion 106 is vulcanized in a state where air is accumulated. The molding was completed, and as a result, a crown bear was generated on the tread surface of the tread portion of the tire. In addition, the opening edge of the sipe of the tire cannot be angled and tends to be formed in a rounded shape. In this sipe shape, the edge effect due to the sipe cannot be sufficiently obtained.

Accordingly, in the tire after vulcanization molding, there is a trade-off relationship between the reduction in the number of spews and the suppression of crown bears, and it has been difficult to achieve both at present.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to improve the number of vent holes provided by optimizing the shape of the corner formed by the surface of the blade and the inner surface of the mold. An object of the present invention is to provide a tire vulcanizing mold that can effectively remove air from the vulcanizing mold during vulcanization molding even when the amount of vulcanizing mold is reduced as compared with that of the vulcanizing mold.

Another object of the present invention is to vulcanize and mold using the above tire vulcanizing mold to reduce the number of spews formed after vulcanization and to prevent the generation of crown bears. The object of the present invention is to provide a tire having a uniform ground contact pressure distribution and an excellent surface appearance, particularly a tire having a block pattern.

[0013]

To achieve the above object, a tire vulcanizing mold of the present invention is a tire vulcanizing mold having a sipe forming blade and an air vent vent hole provided on the inner surface of the mold. In the die, a built-up portion is provided at a corner formed by the blade and the inner surface of the die, the surface being an inclined surface having a linear cross-sectional shape.

Further, it is preferable that the inclined surface of the build-up portion has an angle of intersection with the inner surface of the mold of 135 to 155 °, and the build-up portion has a surface of the blade and the metal mold. The maximum value of the dimension measured along the inner surface of the mold is 0.5-
It is preferably in the range of 1.5 mm.

Furthermore, the tire vulcanization mold of the present invention has a so-called block pattern in which the land portion of the tread is composed of a plurality of blocks, and a tire vulcanization mold having three or more sipes in each block is added. More preferably, it is configured as a metal mold. Incidentally, the inner surface of the mold is usually provided with a protrusion that forms a groove for dividing the land portion of the tread into blocks, and in this case, the vent hole is formed between the blades and between the blade and the protrusion. The number of vent holes is set in the small section sandwiched between them.
It is more preferred to limit it to a range of 30-55% of the total number of said parcels.

Further, a tire can be manufactured by using the above-mentioned vulcanizing mold of the present invention. In such a tire, the opening edge of the sipe formed by the overlaying portion is chamfered into a linear sectional shape. It has a tapered surface and the angle of intersection between the tapered surface and the land surface of the tread is in the range of 135 to 155 °, which has a uniform contact pressure distribution and a good surface appearance, and sipes of the sipe. It is preferable in that the edge can exhibit a sufficient edge effect.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. Figure 1
2 is a plan view of a part of the tire vulcanizing mold according to the present invention, and FIG. 2 (a) is a sectional view taken along line I-I of FIG.
(b) is an enlarged view of a region A surrounded by a solid line shown in (a) of the figure, in which 1 is a tire vulcanizing mold, 2 is a mold inner surface, 3 is a blade, 4 is a vent hole, Reference numeral 5 is a groove forming projection, 6 is a corner portion, and 8 is a built-up portion.

The tire vulcanization mold 1 shown in FIG. 1 is for manufacturing a tire having a block pattern.
The inner surface 2 of the mold is provided with a blade 3 for forming a sipe in the tread land portion of the tire, and a vent hole 4 for bleeding air inside the mold, as well as the tread land portion of the tire. A protrusion 5 is provided which forms a groove for dividing each block.

The main structural features of the present invention are as follows.
The purpose is to optimize the shape of the corner 6 formed by the blade 3 and the mold inner surface 2, and more specifically, the corner 6 formed by the blade 3 and the mold inner surface 2 has a surface Is to provide the built-up portion 8 which becomes the inclined surface 7 having a linear cross-sectional shape. By adopting this configuration, the number of the vent holes 4 to be provided is smaller than that of the conventional vulcanizing mold. Even if the amount is reduced, it is possible to effectively remove air from the vulcanization mold during vulcanization molding.

That is, as shown in FIG. 3, when a tire is vulcanized and molded using a conventional vulcanizing mold having a corner with an angle formed by the surface of the blade and the inner surface of the mold, As shown in FIG. 4, the blade 102 and the mold inner surface 101
The rubber 107 of the tire cannot be sufficiently moved to the corner 106 formed by, and a gap 108 is likely to occur, and if the vent hole 105 is not provided between the blades 102 and 102, the air will flow into the corner 106. The vulcanization molding was completed in the accumulated state, and as a result, a crown bear was generated on the tread surface of the tread portion of the tire. By providing the built-up portion 8 having the proper shape, the rubber of the tire is moved so as to be completely filled in the space defined by the two blades 3 and 3 and the inner surface 2 of the mold without forming a gap. Therefore, the air inside the mold can be effectively discharged to the outside as compared with the conventional vulcanizing mold.

The inclined surface 7 of the built-up portion 8 preferably has an angle of intersection θ with the inner surface 2 of the mold of 135 to 155 °. If the intersection angle θ is larger than 155 °, the blade 3
This is because there is a tendency that air will accumulate at the intersection of the inclined surface 7 and when the angle is smaller than 135 °, air will tend to accumulate on the inner surface 2 of the mold.

The built-up portion 8 is the surface of the blade 3.
Maximum dimension x measured along 3a and said mold inner surface 2
The maximum value y of the dimension measured along
It is preferably in the range of m. The maximum value x is 0.5m
If it is less than m, the inclined surface 7 is too small, and if it is more than 1.5 mm,
This is because it is too large, and the maximum value y is 0.5 mm.
If it is less than 1.5 mm, the distance between the blades will be wider, and it will be 1.5 mm.
This is because if it exceeds the limit, the width becomes narrower, and as a result, the effect of reducing the air pool is small.

Further, the tire vulcanizing mold having the above structure has a so-called block pattern in which the land portion of the tread is composed of a plurality of blocks, and vulcanizes the tire having three or more sipes in each block. It is preferable to configure it as a mold in order to effectively obtain the effects of the present invention.

In this case, the vent hole 4
Are arranged in the small sections 9 of the mold inner surface 2 sandwiched between the blades 3 and 3 and between the blades 3 and the projections 5, and the number of vent holes 4 is 30 of the total number of the small sections 9. It is preferable to limit the range to 55%. If it is less than 30%, the air bleeding effect tends to be insufficient, and if it exceeds 55%, the effect on the appearance is small.

The tire manufactured using the above-mentioned vulcanizing mold can reduce the number of spews formed after vulcanization molding and prevent the generation of crown bears.
The contact pressure distribution is uniform and the surface appearance is excellent.

In particular, in such a tire, the opening edge of the sipe formed by the built-up portion of the vulcanization mold has a tapered surface chamfered into a linear cross section, and this tapered surface It is preferable that the angle of intersection with the land surface of the tread is in the range of 135 to 155 ° in order to make the opening edge of the sipe square and obtain a sufficient edge effect. The intersection angle is 135 °
If it is less than 155 °, the edge effect is small, and if it exceeds 155 °, the effect is reduced.

The above is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims. For example, in FIG. 1, the vulcanization mold for a tire having a block pattern has been described as an example, but the present invention is directed to the inner surface of the mold between the blades for forming sipes and between the blades and the groove-forming projections. Needless to say, it can be applied to all the tire vulcanizing molds that exist.

[0028]

EXAMPLES Next, a tire vulcanizing mold according to the present invention was prototyped and its performance was evaluated, which will be described below. The tire vulcanization mold of the example has a mold inner surface shape shown in FIG. 1 and is a vulcanization mold for manufacturing a tire having a block pattern. The build-up portion is formed in a triangular cross-sectional shape. , The angle of intersection θ of the inclined surface with the inner surface of the mold is 135 °, the maximum values of the build-up portion are 0.5 mm and 1.5 mm, respectively, and the number of vent holes arranged is the total number of the small sections. It was set to 50%. For comparison, the mold has the inner surface shape shown in FIG. 3, the corner portion is not provided with a built-up portion, and one vent hole is provided for each of the small sections. Of 10
The composition was set to 0%, and other configurations were the same as those of the tire vulcanizing mold of the example.

A green tire having the following constitution was vulcanized and molded using each of the above tire vulcanization molds, and a finishing process including a spew removing process was performed to obtain a product tire, and the performance of the product tire was evaluated.

Tire type: Studless pneumatic tire for passenger cars Tire size: 205 / 65R15 Carcass: Polyethylene terephthalate (PET) cords with a cord structure of 1000d / 2 are radially arranged 2
Laminated belt with a single rubber-coated ply: The cords of the two-layer cord layer in which the cord structure is rubber-coated with steel cords of 1 × 5 extend in an angle direction of ± 22 ° with respect to the tire circumferential direction. Stacked. Angle of intersection between the tapered surface of the block and the land surface of the tread: 135 °

(Performance Evaluation) The tires of the conventional example and the example are
A second block row is constructed from the blocks where the entire block is in the contact area when it is mounted on a standard rim (6JJ) and grounded under the conditions of tire internal pressure: 200 kPa and tire load: 3.9 kN The contact area of one block having the same pitch length was calculated, and the uniformity of the contact pressure distribution was evaluated from this.

Here, the "tire load load" is the maximum load (maximum load capacity) of a single wheel in the applicable size described in the following standards, and the "tire internal pressure" is
The air pressure corresponding to the maximum load (maximum load capacity) of a single wheel in the applicable size listed in the standard below. The "standard rim" is the standard rim (or the standard rim in the applicable size listed in the standard below). , “Approved Rim”,
"Recommended Rim"). The "standard" is defined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Bo
ok ”and in Europe“ The European Tire and Rim Te
It is a "Standards Manual" of the chnical Organization, and in Japan it is regulated by the "JATMA YEAR BOOK" of the Japan Automobile Tire Manufacturers Association.

As a result, when the ground contact area of the tire manufactured by the conventional vulcanization mold was 100, the ground contact area of the tire manufactured by the vulcanization mold of the example was as wide as 103.
Further, the tire manufactured with the vulcanizing mold of the example has the number of spews reduced by half compared to the tire manufactured with the vulcanizing mold of the conventional example, and a good surface appearance is obtained, and the sipe edge is obtained. The effect was high. In addition, when vulcanization molding was performed using the vulcanization mold of the example, the number of spews formed on the tire was reduced, and the number of man-hours required for removing spews was reduced, thus improving workability.

[0034]

According to the tire vulcanization mold of the present invention, even when the number of vent holes provided is reduced as compared with that of the conventional vulcanization mold, the vulcanization mold used for vulcanization molding is reduced. It is possible to effectively remove air from the metal mold. In addition, when the number of vent holes provided is reduced, the number of spews formed on the tire is reduced, and as a result, the number of man-hours for removing spews is reduced, resulting in improved workability. it can. Further, by performing vulcanization molding using the tire vulcanization mold, it is possible to reduce the number of spews formed after vulcanization molding and prevent the generation of crown bears, so that the contact pressure distribution is uniform and the surface appearance is It is possible to provide an excellent tire, especially a tire having a block pattern.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a tire vulcanizing mold according to the present invention.

2 (a) is a sectional view taken along the line I-I shown in FIG. 1, and FIG. 2 (b) is
It is an enlarged view of the area | region A shown to (a).

FIG. 3 is a sectional view of a main portion of a tire vulcanizing mold of a conventional example.

FIG. 4 is a view for explaining a problem of the tire vulcanizing mold of FIG.

[Explanation of symbols]

1 Tire vulcanization mold 2 Mold inner surface 3 blades 4 vent holes 5 Groove forming protrusion 6 corners 7 slope 8 Overlay part 9 subdivisions

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Claims (6)

[Claims] 1. A tire vulcanizing mold having a sipe forming blade and an air vent vent hole provided on the inner surface of the mold, wherein a surface is formed at a corner formed by the blade and the inner surface of the mold. A tire vulcanizing mold, characterized in that it is provided with a built-up portion which is an inclined surface having a linear cross-sectional shape. 2. The tire vulcanizing mold according to claim 1, wherein the inclined surface of the built-up portion has an angle of intersection with the inner surface of the mold of 135 to 155 °. 3. The built-up portion has a maximum value of 0.5 measured along the surface of the blade and the inner surface of the mold.
The tire vulcanization mold according to claim 1 or 2, which has a range of from 1.5 mm to 1.5 mm. 4. The tire vulcanization mold has a so-called block pattern in which a land portion of a tread is composed of a plurality of blocks, and a vulcanization mold for a tire having three or more sipes in each block. Claim 1, 2 or 3 configured as
Tire vulcanization mold described. 5. An inner surface of the mold is further provided with a protrusion forming a groove for dividing the land portion of the tread into blocks, and the vent hole is formed in a small section sandwiched between the blades and between the blade and the protrusion. The tire vulcanizing mold according to claim 4, wherein the number of vent holes provided is limited to 30 to 55% of the total number of the small sections. 6. A tire manufactured using the vulcanizing mold according to claim 1, wherein an opening edge of the sipe formed by the built-up portion of the vulcanizing mold has a straight line. A tire having a tapered surface with a chamfered cross section and an angle of intersection between the tapered surface and the land surface of the tread being in the range of 135 to 155 °.